The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Cylinders of an engine may be deactivated to improve fuel economy and reduce emissions. The cylinders may be deactivated by halting generation of spark within the cylinders, halting delivery of fuel to the cylinders, and disabling intake and exhaust valves of the cylinders. In some engines, each intake and exhaust valve may be independently disabled, providing the ability to continuously adjust the number of deactivated cylinders and/or to adjust which cylinders are deactivated.
Deactivating cylinders of an engine may cause significant variation in engine speed. Engine control systems typically use the engine speed to determine target actuator values such as target spark timing, a target cam phaser position, and a target torque converter slip. Thus, variation in the engine speed due to cylinder deactivation may cause undesired variation in the target actuator values.